Ackie Monitor Humidity Requirements

ackie monitor humidity - ackie in burrow
Photo contributed by Jordan Vos

Water is one of the most critical elements of life. That’s why people are so obsessed with finding it on other planets — where there’s water, there’s bound to be life. So even in environments that we think of as fairly dry and arid, water is still required to sustain the life there. As such, you need to consider ackie monitor humidity as you set up your enclosure.

Air Humidity

At first glance, ackie monitor humidity appears to be nonexistent — after all, they live in an incredibly dry environment. Their habitat is sandy soil, with lots of rocks, and the main form of vegetation is drought-resistant spinifex grass. However, there’s more moisture there than you’d think.

According to a collection of relative humidity readings from confirmed ackie territory (Alice Springs, Northern Territory, Australia) in 2020 recorded by, relative humidity levels can be anywhere between 6-100%, depending on the season, weather, and time of day. However, if you take an average of the daily highs and lows, you get a year-round average of 22-38% during the day, and 30-47% during the night. That’s not quite so dry, is it?

Using this data, ReptiFiles recommends average ambient humidity levels between 20-50% for ackie monitors. Occasional dips lower or spikes higher than this range are unlikely to be harmful.

Track your ambient humidity levels with a device like the Exo Terra Digital Hygrometer, with the probe placed in the middle of the enclosure. Alternatively, you can use a high-quality wall-mounted digital hygrometer, such as the Govee Smart Temperature and Humidity Monitor, placed within 12″ of the ground, in the middle of the enclosure.

Substrate Humidity

For ackie monitors, substrate moisture content is generally more important than ambient humidity. The substrate should be moist enough to create burrow humidity levels of 80% or higher.

In dry climates, many reptiles will burrow deep into the sand or soil in order to access pockets of humidity and prevent dehydration. According to Water and Energy Turnover in a Small Monitor Lizard, Varanus acanthurus by Gil Dryden et al., spending lots of time in shelters like burrows is noted to help reduce water loss in monitor lizards with semi-arid habitats.

The difference between burrow/substrate humidity and air humidity can be striking. While on a herping trip to Australia, Dāv Kaufman measured humidity levels of 90% inside an ackie burrow!

Your substrate should be moist enough for it to clump and hold form, which is essential to creating burrows that won’t collapse. One way to make sure your substrate stays moist is to bury another digital hygrometer probe and add water when it gets too dry. When substrate moisture drops below 80%, it’s time to remoisten. One of the best ways to rehydrate your substrate is with a watering can with a shower head like this one.

If possible, use a sheet of thick glass as the enclosure’s substrate barrier. This enables you to get a visual on the substrate’s moisture content. The substrate should be moist enough to get darker in color and form condensation on the glass.


  • Humidity is important to hydration
  • Ambient humidity: average 40-60%
  • Substrate should be moist enough to clump
  • Re-wet the substrate by pouring water into it
  • Substrate moisture is more important than ambient humidity

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